The Greek Orthodox Patriarchate of Jerusalem, also known as the Greek Orthodox Church of Jerusalem, is an autocephalous church within the wider communion of Eastern Orthodox Christianity. Established in the mid-fifth century as one of the oldest patriarchates in Christendom, it is headquartered in the Church of the Holy Sepulchre in Jerusalem and led by the Patriarch of Jerusalem, currently Theophilos III. The Patriarchate's ecclesiastical jurisdiction includes roughly 200,000 to 500,000 Orthodox Christians across the Holy Land in Palestine, Jordan and Israel. The church traces its foundation in Jerusalem to the day of Pentecost, when the Holy Spirit, according to Christian beliefs, descended on the disciples of Jesus Christ and ushered the spread of the Gospel. The church celebrates its liturgy in the ancient Byzantine Rite – whose sacred language, Koine Greek, is the original language of the New Testament – and follows its own liturgical year under the Julian calendar. The majority of Orthodox Christians under the Patriarchate are Palestinians and Jordanians, with minorities of Russians, Romanians, and Georgians. However, the church's hierarchy is dominated by Greek clergy, which has been a source of recurring tension and dispute. A movement to Arabize the church is known as the Arab Orthodox Movement, that began in the 19th century. The church serves as custodian of several holy places in Christianity, including the Church of the Nativity, in Bethlehem, where Jesus is said to have been born, and the Church of the Holy Sepulchre in Jerusalem, which includes the site of Jesus' crucifixion and the empty tomb from which he is believed to have resurrected.